On December 24, 1601, Hugh O’Neill, Earl of Tyrone, and his Spanish and Irish allies are defeated by the English at the Battle of Kinsale, one of the most important battles in Irish history. With the able assistance of his main ally, Hugh Roe “Red” O’Donnell, he is fighting to defend Gaelic Ireland against the forces of Elizabeth I of England.

O’Neill, along with O’Donnell, train an army and before long they find a powerful ally, King Phillip III of Spain. King Phillip is more than keen to help the Irish for two reasons. Firstly, he wants revenge for the famous defeat of his Spanish Armada in 1588 and secondly, he sees Ireland as a terrific foundation from which he can invade England.

King Phillip agrees to the request of O’Neill and O’Donnell to send a large army to help them defeat the English. For several years prior they had held the English at bay from the strongholds in Ulster, beating them at Yellow Ford in 1598 and Moyry Pass in 1600. But if they are to ever drive the English back across the Irish Sea, they have to come out from the hills and passes and meet them in open battle. King Phillip eventually sends his army of 4,800 men to Kinsale in County Cork, thirteen miles south of Cork, arriving on September 21, 1601. They are surrounded by the English army, led by Charles Blount, 8th Baron Mountjoy, and George Carew, 1st Earl of Totnes, the President of Munster.

The landing of the Spanish army is not where O’Neill would have hoped as he and O’Donnell are located in the northern county of Donegal. He had sent a message asking them to land further north, so they might join forces and march against the English, but that message either never arrives or arrives too late. Now O’Neill and O’Donnell face a long march to join with their allies, and the English are much closer to Kinsale than they.

Before the Irish can get there, Mountjoy’s army has laid siege to the Spaniards at Kinsale. To leave their northern strongholds holds many dangers for the Irish chieftains, but leave they do, marching their army 250 miles to Kinsale to put the future of Gaelic Ireland to the test on the battlefield, a march which many say is one of the greatest marches to date in Irish History.

On the morning of December 24, O’Neill moves to attack Mountjoy’s army. There is no coordination between O’Neill’s army and the Spanish in Kinsale, under Don Juan del Águila. The Spaniards make no attempt to attack in force or even create a diversion. O’Neill’s army, especially his cavalry, which perform badly, are not ready to meet the English in this sort of combat. The battle lasts only an hour, with Irish losses of 1,200 soldiers whereas the English lose only twenty. The critical battle of the Nine Years’ War has been lost.

Afterwards, O’Donnell flees to Spain where he lives comfortably until he dies a few months later, said to have been poisoned by a spy of Carew’s named Blake.

Hugh O’ Neill surrenders to the English in 1603 and later returns to Ulster, where Lord Mountjoy treats him respectively well. However, most of his lands and authority are non-existent. In 1607, he goes to Spain with a number of family members and supporters, most of whom are lesser chieftains, and this becomes famously known as the Flight of the Earls. The power of the Gaelic chiefs in Ireland become a thing of the past.